Characteristics of podocyte injury in malignant hypertensive nephropathy of rats (MSHRSP/Kpo strain)

Prakash. Nephrin a biomarker of early glomerular injury in newly diagnosed untreated hypertensive subjects

Introduction and Aim: Hypertension and proteinuria is known to cause renal and cardiovascular disease and mortality in patients irrespective of diabetes. It is beneficial to identify proteinuria and probable glomerular injury early to take preventive measures from cardiovascular event.  In our study, we aimed to evaluate whether a biomarker such as nephrin can detect early glomerular injury in treatment naïve hypertensive subjects.   Materials and Methods: Forty newly diagnosed, treatment naïve hypertensive subjects were recruited for the study along with 40 normotensive controls after obtaining informed consent and procuring approval from. Institutional Ethics Committee. The hypertensive group was classified as diabetic and non-diabetic hypertensives and compared with apparently healthy controls (normotensive). Urine sample was analyzed for microalbumin, creatinine and nephrin. Blood sample was analyzed for glycated hemoglobin, urea, creatinine, sodium, and potassium.  Statistical analysis was performed using ANOVA to compare the groups for various parameters. Odds ratio was calculated.   Results: Hypertensives were sub-grouped based on amount of microalbumin excreted. Urine nephrin excretion was significantly higher in hypertensive subjects than normotensive subjects (nephrin cut-off: 0.09 mg/g of creatinine). Urine nephrin (mg/g) was found to be elevated (median 0.15; interquartile range, 0.12 and 0.17) in hypertensives with normoalbuminuria and it was significantly higher than normotensive subjects (median 0.07; interquartile range, 0.04 and 0.09).     Conclusion: Urine nephrin may be used as a biomarker of early glomerular injury in hypertensive subjects even before microalbuminuria is detected.

Association between long-term pulse pressure trajectories and risk of end-stage renal diseases in incident malignant hypertensive nephropathy: a cohort study

OBJECTIVE

The trajectories of pulse pressure (PP) might affect the prognosis of malignant hypertensive nephropathy (MHN). We aimed to describe the association between PP trajectories and the future risk of end-stage renal disease and to identify and compare the associated patient characteristics of any distinct trajectory patterns in MHN patients.

METHODS

Patients with newly diagnosed biopsy-proven MHN 2010-2015 were included. Latent class growth analysis was applied to the PP measured over 3 years prior to biopsy to identify distinct trajectories. Concurrent systolic blood pressure, diastolic blood pressure, plasma creatinine, and 24-h urine protein measurements for each trajectory group were modelled using generalized estimating equations. The risk of end-stage renal disease (with kidney replacement therapy as a proxy) was estimated using Logistic regression.

RESULTS

Two hundred three patients were included (median-age 34 years, and 19.7% female). A two-group cubic model was optimal, with trajectories distinguished by the rate of PP and absolute level at final measurement. Trajectory Group-1 (n = 84) was characterized by 'first-increased-then-decreased' PP and trajectory Group-2 (n = 119) was characterized by 'first-decreased-then-increased' PP over 3 years prior to biopsy. Systolic and diastolic blood pressures, plasma creatinine, and 24-h urine protein were differed by the trajectory group. Baseline characteristics differed substantially between trajectory groups. Compared with Group-1, Group-2 had a 66% greater risk of developing into end-stage renal disease in the subsequent 3 years.

CONCLUSIONS

Two distinct 3-year trajectories for PP exist with MHN. Early introduction of intensive antihypertensive treatment might delay the development of end-stage renal disease among patients with malignant hypertension.

Research Progress in Acute Hypertensive Renal Injury by "in Vivo Cryotechnique"

Arterial hypertension has a large prevalence in the general population and as a major hypertensive target organ, the involvement of kidney is usually hard to avoid and gradually develops into chronic kidney disease (CKD). Acute hypertension is defined as a blood pressure greater than 180/120, also known as hypertensive emergency (HE). In acute severe hypertension, the pathophysiology damage to the kidney tends to worsen on the basis of chronic damage, and accounts for more significant mortality. However, the mechanisms of renal injury induced by acute hypertension remain unclear. This review summarizes the clinical and histopathological features of hypertensive renal injury by using "in vivo cyrotechnique" and focusses on the interplay of distinct systemic signaling pathways, which drive glomerular podocyte injury. A thorough understanding of the cellular and molecular mechanisms of kidney damage and repair in hypertension will provide significant insight into the development of new research methods and therapeutic strategies for global CKD progression.

Human podocyte injury in the early course of hypertensive renal injury

BACKGROUND

Hypertension is prevalent in the general population and is regarded as the second leading cause of renal damage and dysfunction, outnumbered only by diabetes. However, the mechanisms remain unclear.

AIM

To investigate podocyte injury induced by hypertension in the early course without massive proteinuria or renal dysfunction.

METHODS

The hypertension group comprised 18 patients with hypertension accompanied by microalbuminuria, diagnosed with hypertensive renal injury according to biopsy results. For a comparison of pathological changes in renal tissue, control group 1 comprised 10 healthy volunteers, and control group 2 comprised 16 patients who underwent surgery for renal trauma.

RESULTS

The hypertension group had significantly higher blood pressure (P = 0.000) and microalbuminuria (P = 0.000) compared with control group 1. In the hypertension group, urinary podocytes were detected following positive staining of podocyte-specific nephrin and/or CD2-associated protein (CD2AP) in urine sediment. Podocyte foot process fusion and a significant decrease in nephrin and/or CD2AP expression in glomeruli were observed in the hypertension group compared with control group 2. This indicated that hypertension caused podocyte injury and detachment from the glomerular basement membrane, which was consistent with urinary detection of podocytes.

CONCLUSION

Our results suggest that podocyturia appears early in the course of hypertensive renal injury, and may be a sensitive marker for early prediction of hypertensive renal injury.

p66Shc regulates podocyte autophagy in high glucose environment through the Notch-PTEN-PI3K/Akt/mTOR pathway

BACKGROUND AND AIMS

Autophagy has been found to be involved in podocyte injury, which is a key factor in the progression of diabetic kidney disease (DKD). p66Shc is an important protein adaptor that regulates production of reactive oxygen species (ROS) and induction of apoptosis, and is a novel biomarker for oxidative damage of renal tubules. Our preliminary studies showed that p66Shc expression in podocytes of DKD patients is increased, while autophagic flux and podocyte number is decreased in DKD patients. The mechanism by which p66Shc may regulate podocyte autophagy and injury remains unknown. The present study aimed to investigate the molecular function of p66Shc under high glucose condition and its possible therapeutic utility in DKD.

METHODS

We histologically evaluated kidney injury in a streptozocin (STZ)-induced mouse model of diabetes using HE, PAS, PASM, and Masson staining and assessed glomerular structure by transmission electron microscopy. The apoptosis rate of high glucose-treated podocytes was assessed by TUNEL and Annexin V/PI staining. Markers of podocyte autophagy were measured by immunofluorescence and western blotting. DHE/ET fluorescence quantification was used for ROS detection and quantification.

RESULTS

Urine creatinine, serum creatinine, urinary microalbumin, and p66Shc expression were significantly increased in STZ-induced diabetic mice. Cultured MPC5 podocytes subjected to high glucose showed reduced viability, and p66Shc overexpression further accelerated apoptosis. p66Shc knockdown enhanced HG-induced autophagy, while p66Shc overexpression reduced the expression of PTEN and increased the expression of mTOR and phospho-mTOR. LC3 protein expression was higher in cells with p66Shc knockdown, indicating that activation of p66Shc inhibits podocyte autophagy. DAPT, an inhibitor of the Notch pathway, downregulated the expression of p66Shc.

CONCLUSION

These findings indicate that p66Shc inhibits podocyte autophagy and induces apoptosis through the Notch -PTEN-PI3K/Akt/ mTOR signaling pathway in high glucose environment, providing novel evidence for its potential role in DKD treatment.